What is the visual range of a PML?

• A. 0.5 nautical miles
• B. 1 nautical mile
• C. 2 nautical miles
• D. 3 nautical miles

Answer: (D)

Visual range is the distance at which a light can be seen by an observer at a typical eye height above the water, under standard conditions. For a PML, the specified nominal range is three nautical miles, meaning under normal conditions the marker light should be visible from about three miles away. This distance balances visibility for mariners approaching or leaving a harbor with reasonable power usage and brightness.

Shorter ranges would make the marker harder to spot at practical distances, while longer ranges aren’t typically required for this type of marker in standard operating environments. Actual visibility can vary with observer height, weather, and atmospheric conditions, but three nautical miles is the standard expectation for a PML.